Curable epoxy resins

Abstract

A curable resin is composed of A. an epoxy resin and B. a pyrylium salt as a catalyst, with or without C. a metal chelate or metal salt as a co-catalyst. Preferred pyrylium salts are those of the formula ##STR1## Preferred co-catalysts are acetylacetonates, stearates, benzoates, naphthenates, octoates or phthalates of Cu ++ , Co ++ , Co +++ , Fe +++ or Al +++ . The resin compositions may be used to produce coatings and moldings.

We claim: 
     
       1. A curable resin composition, containing A. a cationic polymerizable epoxy resin, and   B. from 0.5 to 10% by weight of an onium salt as a hardening catalyst, wherein the catalyst is a pyrylium salt of the formula ##STR13##  where R 1  and R 5  are identical and are each alkyl or alkaryl, each of 1 to 8 carbon atoms, R 2 , R 3  and R 4  are identical or different and are each hydrogen, or alkyl, alkaryl or cycloalkyl, each of not more than 8 carbon atoms, or an unsubstituted or alkyl-substituted phenyl, naphthyl, indenyl, indanyl or fluorenyl group or a heterocyclic substituent containing one or two heteroatoms, and X.sup.⊖ is a non-nucleophilic anion.   
     
     
       2. A curable resin composition as claimed in claim 1, wherein the composition additionally contains from 0.01 to 10% by weight of metal chelate (C 1 ) of the formula ##STR14## where Me is a monovalent, divalent, trivalent or tetravalent metal, R 7  is hydrogen, or alkyl, cycloalkyl, aryl or alkaryl, each of not more than 8 carbon atoms, and R 6  and R 8  are identical or different and are each alkyl, cycloalkyl, aryl, aralkyl or alkaryl, each of not more than 8 carbon atoms, wherein R 6  and R 8  may furthermore be bonded to one another by a ring system, and n is an integer from 1 to 4. 
     
     
       3. A curable resin composition as claimed in claim 1, wherein the composition additionally contains from 0.01 to 10% by weight of a metal salt (C 2 ) of an aliphatic or aromatic mono- or polycarboxylic acid of 6 to 20 carbon atoms. 
     
     
       4. A curable resin composition as claimed in claim 1, wherein the catalyst is a pyrylium salt of the formula ##STR15## where R 3  has the meanings given in claim 1 and X.sup.⊖ is AsF 6 .sup.⊖, BF 4 .sup.⊖, SbF 6 .sup.⊖, PF 6 .sup.⊖, CF 3  SO 3 .sup.⊖ or ClO 4 .sup.⊖. 
     
     
       5. A curable resin composition as claimed in claim 2, wherein the metal chelate is an acetylacetonate of Cu ++ , Co ++ , Co +++ , Fe +++   or Al +++ . 
     
     
       6. A curable resin composition as claimed in claim 3, wherein the metal salt is a stearate, benzoate, naphthenate, octoate or phthalate of Cu ++ , Co ++ , Co +++ , Fe +++  or Al +++ . 
     
     
       7. A process for the production of a molding from the resin composition as claimed in claim 1, wherein an epoxy resin A is mixed thoroughly with the catalyst B, with or without a co-catalyst C 1  or C 2 , and the mixture is heated at from 80° C. to 160° C.